| Abstract | U ovom radu je napravljen proračun energetskog potencijala kombiniranog ciklusa koji se sastoji od Braytonovog, Rankineovog i Organskog Rankineovog ciklusa (ORC). U Braytonovom dijelu radni medij je zrak, u Rankineovom dijelu radni medij je voda i u ORC dijelu je odabran R245fa kao organski radni medij.
U Braytonovom ciklusu nema izgaranja pa se ciklus odvija bez emisija ugljikovog dioksida. Braytonov ciklus dobiva toplinu preko izmjenjivača topline taljene soli (ITTS-a) kojeg s toplinom opskrbljuje centralni prijemnik heliostatskog polja. U generatoru pregrijane pare s povratom topline (GPPPT) se toplina odbačenog zraka plinske turbine predaje Rankineovom parnom ciklusu, a zatim se višak toplinske energije zraka nakon prve izmjene topline u GPPPT, usmjerava prema generatoru pare s povratom topline (GPPT) gdje predaje toplinsku energiju radnom mediju Organskog Rankineovog ciklusa.
Testiran je energetski potencijal kombiniranog ciklusa i promotren je utjecaj odsutnosti ORC i Rankineovog dijela na vrijednosti kombiniranog ciklusa. Nakon modeliranja ciklusa zaključeno je da je optimalna temperatura zraka na izlazu iz ITTS-a između 950 do 1000 °C. Također je utvrđeno da je R245fa optimalni izbor za organski radni medij te je konstatirano da optimalan tlak zraka na izlazu iz kompresora iznosi 2400 kPa. Za optimalan tlak visokotlačne turbine (VTT) koji iznosi 5000 kPa, za postizanje većeg stupnja djelovanja neophodno je da temperatura pare na ulazu u VTT i niskotlačnu turbinu (NTT) bude iznad 264 °C, odnosno iznad temperature zasićenja radnog medija. Sve analize i proračuni su urađeni u EES (engineering equation slover) softverskom paketu. |
| Abstract (english) | In this paper the energy potential of a combined Bryton, Rankine and ORC cycle is calculated. In the Brayton part, the working fluid is air, in the Rankine part, the working fluid is water, and in the ORC part, pentafluorpropane (R245fa) is chosen as the working fluid.
In the Brayton cycle, there is no combustion, so the cycle operates without CO2 emissions. The Brayton cycle receives heat through a molten salt heat exchanger (MSHE), which is supplied with heat by the heliostat field receiver. In the heat recovery vapour generator (HRVG), the heat from the exhaust air of the gas turbine is transferred to the Rankine steam cycle, and then the excess thermal energy of the air, after the first heat exchange with the steam, is directed towards the heat recovery steam generator (HRSG), where it transfers thermal energy to the working fluid of the organic Rankine cycle.
The energy potential of the combined cycle is theoretically tested, and the impact of the absence of the ORC and Rankine parts on the values of the combined cycle is observed. The values of the cycle are presented in table 5.1, and the cycle process is shown in T-s and h-s diagrams. After modeling the cycle, it was concluded that the optimal air temperature at the exit of the MSHE is between 950 to 1000 °C. It was also determined that R245fa is the optimal choice for the organic working fluid, and it was also found that the optimal air pressure at the compressor outlet is 2400 kPa. For the optimal pressure of the high-pressure turbine, which is 5000 kPa, to achieve a higher degree of efficency, it is necessary that the temperature of the steam at the entrance to the high-pressure turbine and the low-pressure turbine be above 264 °C, i.e. above the saturation temperature of the working medium. All analyzes and calculations were made in the EES (engineering equation solver) software package. |
